Implementing a dual-touch 4-wire analog resistive touchscreen via regression analysis

Abstract

As touch mania sweeps across many applications, a large number of venders seek to upgrade to dual-touch if not to multi-touch features, but cannot justify the price of capacitive touchscreens. To get around this, other methods - both legacy and cutting edge – are available. The idea is to create inexpensive alternatives to capacitive touchscreens or retrofit dual-touch/multi-touch gestures to existing resistive-touchscreen designs, for example. This paper introduces a new scheme to detect any dual-touch on an analog resistive touchscreen. A 4-wire version was chosen due to the simplicity of its structure. Both linear and polynomial regression, was used to support the ability of detecting any position. Four screen sizes, 4.3-inch, 5.7-inch, 7-inch, and 10.2-inch, were explored. The findings revealed that resistance changes during touch can be utilized for detecting the coordinates of finger(s), for a single-touch and any dual-touch. The maximum error across all screen sizes, evaluated by RMSE, is under 3mm from the exact position on both the X and Y-axes.